2.8. Transmission Electron Microscopy
Samples were fixed with 2.5% glutaraldehyde and 1% osmic acid overnight at 4°C for 1.5 h and then washed with phosphate-buffered saline (PBS) thrice for 15 min. The samples were dehydrated with different concentrations of gradient ethanol (30%, 50%, 70%, 80%, 90%, 95%, and 100%) and then embedded in a mixture of embedding agent and acetone at 70°C overnight. Subsequently, 70 nm-thick sections were obtained using a Reichert Jung ultrathin microtome and stained with lead citrate and uranyl acetate. The sections were observed under an H-7650 transmission electron microscope.